Summary: I will first collect the Punnett square questions from the previous day. This will be corrected and used as a formative assessment classwork grade. We will review monohybrid crosses and how to determine genotypic and phenotypic ratios. We will also briefly discuss the concept of independent assortment and the process of constructing a dihybrid cross, which students should have background knowledge about after completing last night's homework. To explain the concept of independent assortment of genes, students will engage in a dihybrid cross activity. The activity is inquiry-based and requires students to create two Punnett Squares and then create an experiment to test their predictions.
Objectives: Students will describe how a dihybrid Punnet Square displays the concept of independent assortment of alleles. Students will successfully cross two traits in a dihybrid Punnett Square and describe the genotypic and phenotypic results that occur. Students will design a procedure that tests the results of their Punnett Square results using coins labeled with certain alleles. Students will compare their observed coin toss results with their expected Punnett Square results.
100 pennies, labeled with Ss and Ee 100 nickels, labeled with Aa and Nn
Instruction: Opening: "Who can summarize what genotypic and phenotypic ratios will result when we cross two heterozygous individuals in a Punnett Square?" -I will make sure students remember the 1:2:1 and 3:1 ratios that result. "We're going to get a little more complicated with the Punnett Squares today. Sometimes geneticists need to predict the probability of an offspring inheriting two different traits. There's a way to do this in one Punnett square, and you read about this last night for homework." -Lead a discussion about the principle of independent assortment. Make sure students see how alleles are split up along a Punnett square to account for this principle. I will model a dihybrid cross on the chalkboard and have students walk me through the process. "Now we'll be doing another inquiry activity- there are aliens who need your help!"
Middle: I will hand out the alien genetics worksheet and explain the activity: 1. Each lab pair obtains 4 coins from each bag at the front of the room. -I will premake the coins with alleles on them. One bag will be pennies with the alleles Ss for skin color, pennies Ee for number of eyes, nickels Aa for the presence of antennae, and nickels Nn for nose shape. 2. Students make a Punnett square for the parental genes they picked out of the bag. In each square, students should have one penny gene and one nickel gene. 3. Once students determine their predicted results, they will design an experiment to test their predictions. -students need to realize that they need to flip the coins multiple times to get the ratios of offspring they obtain in their Punnett squares. I will walk around the room at this time to help any students who are struggling by asking them guiding questions. "How do you think you can use a coin to predict probability?" 4. Students will make a data table and then summarize their results on the worksheet. If they do not finish, it is homework.
Closing:
I will conclude the lesson by asking for students to share their findings. I will inform students of an upcoming quiz before we get into meiosis, so they can start studying their notes and activities that we've done this far.
Homework: Finish the data table and the outcomes section from the dihybrid cross activity. Study for quiz.
Assessments:
1. Formative assessment- I will collect the paragraph written about Independent Assortment and check it off as a homework grade
2. Formative assessment- As students help me explain the terms and concepts, I will be able to judge whether or not they spent time reading the textbook and understanding it.
Summary: I will first collect the Punnett square questions from the previous day. This will be corrected and used as a formative assessment classwork grade. We will review monohybrid crosses and how to determine genotypic and phenotypic ratios. We will also briefly discuss the concept of independent assortment and the process of constructing a dihybrid cross, which students should have background knowledge about after completing last night's homework. To explain the concept of independent assortment of genes, students will engage in a dihybrid cross activity. The activity is inquiry-based and requires students to create two Punnett Squares and then create an experiment to test their predictions.
Objectives:
Students will describe how a dihybrid Punnet Square displays the concept of independent assortment of alleles.
Students will successfully cross two traits in a dihybrid Punnett Square and describe the genotypic and phenotypic results that occur.
Students will design a procedure that tests the results of their Punnett Square results using coins labeled with certain alleles.
Students will compare their observed coin toss results with their expected Punnett Square results.
Materials:
Alien genetics worksheet
100 pennies, labeled with Ss and Ee
100 nickels, labeled with Aa and Nn
Instruction:
Opening:
"Who can summarize what genotypic and phenotypic ratios will result when we cross two heterozygous individuals in a Punnett Square?"
-I will make sure students remember the 1:2:1 and 3:1 ratios that result.
"We're going to get a little more complicated with the Punnett Squares today. Sometimes geneticists need to predict the probability of an offspring inheriting two different traits. There's a way to do this in one Punnett square, and you read about this last night for homework."
-Lead a discussion about the principle of independent assortment. Make sure students see how alleles are split up along a Punnett square to account for this principle. I will model a dihybrid cross on the chalkboard and have students walk me through the process.
"Now we'll be doing another inquiry activity- there are aliens who need your help!"
Middle:
I will hand out the alien genetics worksheet and explain the activity:
1. Each lab pair obtains 4 coins from each bag at the front of the room.
-I will premake the coins with alleles on them. One bag will be pennies with the alleles Ss for skin color, pennies Ee for number of eyes, nickels Aa for the presence of antennae, and nickels Nn for nose shape.
2. Students make a Punnett square for the parental genes they picked out of the bag. In each square, students should have one penny gene and one nickel gene.
3. Once students determine their predicted results, they will design an experiment to test their predictions.
-students need to realize that they need to flip the coins multiple times to get the ratios of offspring they obtain in their Punnett squares. I will walk around the room at this time to help any students who are struggling by asking them guiding questions. "How do you think you can use a coin to predict probability?"
4. Students will make a data table and then summarize their results on the worksheet. If they do not finish, it is homework.
Closing:
I will conclude the lesson by asking for students to share their findings. I will inform students of an upcoming quiz before we get into meiosis, so they can start studying their notes and activities that we've done this far.
Homework: Finish the data table and the outcomes section from the dihybrid cross activity. Study for quiz.
Assessments:
1. Formative assessment- I will collect the paragraph written about Independent Assortment and check it off as a homework grade
2. Formative assessment- As students help me explain the terms and concepts, I will be able to judge whether or not they spent time reading the textbook and understanding it.